12.08.2008

VIDEOSURF’S technology works in part by memorizing components of faces, Dr. Sharon said. It stores away images of Britney Spears’ eyes and cheekbones, for instance, in its collective memory, so it can recognize an image of her despite changes in light. Such expert perception means that the technology can do what many people can’t, he said.

“As videos get longer,” he said, “it’s harder and harder to find the one minute you want to see.”

Click on any one of these images, like the face of a guest on Mr. Stewart’s show, or the face of John Oliver, one of Mr. Stewart’s correspondents, and go directly to that part of the video. Users can also select snippets within a video and send them by e-mail to friends.